P1208 混合牛奶

#include<iostream>#include<cstring>#include<string>#include<algorithm>#include<queue>#include<vector>#include<cstdio> using namespace std;int n,m,ans=0;struct H{    int p,a;}milk[5009];int my_comp(const H&x,const H&y){    if(x.p<y.p) return 1;    return 0;}int main(){    scanf("%d%d",&n,&m);    for(int i=1;i<=m;i++)    {        scanf("%d%d",&milk[i].p,&milk[i].a);    }    sort(milk+1,milk+m+1,my_comp);    for(int i=1;i<=m;i++)    {        if(milk[i].a<=n)        {            ans+=milk[i].p*milk[i].a;            n-=milk[i].a;        }        else         ans+=n*milk[i].p,n=0;        if(n==0) break;    }    printf("%d",ans);    return 0;}